Warren Buffett's Berkshire Hathaway Inc on Tuesday disclosed a new stake in agricultural and construction equipment maker Deere & Co , one of a handful of changes in its stock holdings during the fourth quarter. Berkshire reported a 17.1 million-share stake, according to a U.S. Securities and Exchange Commission filing that detailed its domestic equity investments as of Dec. 31. Buffett began accumulating the position in the third quarter but had not previously disclosed it.